#include <stdio.h>
#include <malloc.h>
#define MaxSize 5
typedef char ElemType;
typedef struct
{
    ElemType data[MaxSize];
    int front,rear;     //队首和队尾指针
} SqQueue;
void InitQueue(SqQueue *&q) //初始化队列
{   q=(SqQueue *)malloc (sizeof(SqQueue));
    q->front=q->rear=0;
}
void DestroyQueue(SqQueue *&q)  //销毁队列
{
    free(q);
}
bool QueueEmpty(SqQueue *q) //判断队列空
{
    return(q->front==q->rear);
}
bool enQueue(SqQueue *&q,ElemType e)    //进队
{
    if ((q->rear+1)%MaxSize==q->front)  //队满上溢出
        return false;
    q->rear=(q->rear+1)%MaxSize;
    q->data[q->rear]=e;
    return true;
}
bool deQueue(SqQueue *&q,ElemType &e)   //出队
{
    if (q->front==q->rear)      //队空下溢出
        return false;
    q->front=(q->front+1)%MaxSize;
    e=q->data[q->front];
    return true;
}
extern void InitQueue(SqQueue *&q);
extern void DestroyQueue(SqQueue *&q);
extern bool QueueEmpty(SqQueue *q);
extern bool enQueue(SqQueue *&q,ElemType e);
extern bool deQueue(SqQueue *&q,ElemType &e);
int main()
{
    ElemType e;
    SqQueue *q;
    printf("环形队列基本运算如下:\n");
    printf("  (1)初始化队列q\n");
    InitQueue(q);
    printf("  (2)依次进队列元素a,b,c\n");
    if (!enQueue(q,'a')) printf("\t提示:队满,不能进队\n");
    if (!enQueue(q,'b')) printf("\t提示:队满,不能进队\n");
    if (!enQueue(q,'c')) printf("\t提示:队满,不能进队\n");
    printf("  (3)队列为%s\n",(QueueEmpty(q)?"空":"非空"));
    if (deQueue(q,e)==0)
        printf("队空,不能出队\n");
    else
        printf("  (4)出队一个元素%c\n",e);
    printf("  (5)依次进队列元素d,e,f\n");
    if (!enQueue(q,'d')) printf("\t提示:队满,不能进队\n");
    if (!enQueue(q,'e')) printf("\t提示:队满,不能进队\n");
    if (!enQueue(q,'f')) printf("\t提示:队满,不能进队\n");
    printf("  (6)出队列序列:");
    while (!QueueEmpty(q))
    {   deQueue(q,e);
        printf("%c ",e);
    }
    printf("\n");
    printf("  (7)释放队列\n");
    DestroyQueue(q);
}